Cluster Headache

Definition/diagnostic criteria Cluster headache, recognised as a primary headache disorder, is characterised by severe, unilateral pain typically around the orbital or temporal areas. The International Classification of Headache Disorders defines cluster headaches as attacks lasting between 15 to 180 minutes, occurring from once every other day to eight times a day, with either one or more cranial autonomic symptoms (e.g. lacrimation, nasal congestion) on the pain side and/or restlessness or agitation.

Epidemiology Cluster headaches are less common than migraines, affecting about 1 in 1,000 people. They show a male predominance, with a male-to-female ratio of approximately 2.5:1. The typical onset is in the 20s or 30s, although they can start at any age.

Diagnosis
Clinical features: Patients with cluster headaches report excruciatingly painful attacks, often described as sharp, burning or piercing. The pain is unilateral, primarily around the eye, temple, forehead or cheek. Accompanying symptoms include ipsilateral lacrimation, nasal congestion, eyelid oedema, forehead and facial sweating, miosis, ptosis, and a sense of restlessness or agitation. Cluster headache attacks are often recurrent and episodic, with periods of remission.

Investigations: Diagnosis is primarily clinical. However, neuroimaging (e.g., MRI) may be recommended to exclude secondary causes in atypical cases. Typical abnormalities are not found in primary cluster headaches, and neuroimaging is usually normal.

Treatment The management of cluster headaches is twofold: acute treatment of attacks and prophylaxis.

• Acute treatment: Subcutaneous sumatriptan and high-flow oxygen are the mainstays of abortive treatment. Sumatriptan (6 mg subcutaneously) is effective and can be repeated if necessary after an hour, with up to two injections in 24 hours. Inhalation of 100% oxygen at 12-15 litres per minute for up to 30 minutes can also provide relief.
• Preventive treatment: Verapamil is the first-line preventive treatment, with the dose titrated to effect and tolerance. ECG monitoring is necessary due to the risk of heart block. Other options include lithium carbonate (especially in chronic cases) and corticosteroids as a short-term bridge therapy. Melatonin and greater occipital nerve injections are additional options.

Prognosis Cluster headaches have a chronic nature with episodic patterns. While remission periods can last for months or years, the condition is often lifelong. The severity and frequency of attacks can vary over time. Quality of life can be significantly affected due to the intensity of pain and unpredictability of attacks. However, with appropriate management, many patients achieve good control of symptoms.